Solid Freeform Fabrication (SFF) is a group of manufacturing technologies that are capable of producing 3D solid parts by a consecutive layer-wise shaping and consolidation of material (e.g. in the form of powder). Part geometric data can be taken directly from a Computer Aided Design (CAD) model and processed to form an object without the need for any moulds or tools. Various materials and combinations of materials such as plastics, waxes, metals and ceramics can be processed according to the process used.
The production of fully functional parts with high densities in a single step often requires the complete melting of powder particles. This can be achieved with the use of high energy densities (e.g. a laser beam or an electron beam) that can generate temperatures capable of fully liquefying powder particles creating a melt pool. Once the heat has been removed from the newly generated melt pool, the molten material solidifies forming a bulk mass often with the generation of new grains within its structure.
The above processes when applied to metal powders often induce a rapid melting and re-solidification of material that causes large internal thermal stresses that may cause a part to warp during and after solidification. Due to warping, certain geometries (such as overhanging/unsupported features which are relatively common in models), need to be forcibly held down to the substrate with anchors that are fabricated during a build. These anchors are usually made from the same metal used to produce the part and are often troublesome and time consuming or impossible to remove after producing the part. Removal of anchors can also damage components causing the part to be unusable.
It would therefore be desirable to provide an alternative method and apparatus for forming an object.